I had installed a Forefront Client Security (FCS) server on a Windows Server 2008.

Fore some reason the FCS clients were not automatic approved in the MOM 2005 Administrator Console. Normally new clients will be approved within 60 minutes from the installation.

In the Application log on the FCS server there were an event id 20607 logged every 60 minutes saying:

The Data Access Server (DAS) on computer localhost returned an error. System error code: -2147024891 System error text: Access is denied. DAS method called: ProcessRuleSelectAll Called from file: d:\bt\4\private\product\config\tools\managementpacksupport\drivers\momdb\src\db2mpsupport.cpp

Asking my friend Google helped me solving the problem. It turned out that the DAS account was not added to the MOM Administrators local group during the installation.

In the last Post in this thread it is explained that "If Client Security server components are installed on a server that has User Account Control (UAC) enabled, you must manually add the DAS account to the MOM Administrators local group." That was exactly what I did and now new clients were auto approved within 60 minutes from installation.